[PATCH 02/22] KEYS: Provide keyctls to drive the new key type ops for asymmetric keys

From: David Howells
Date: Wed Sep 05 2018 - 17:54:38 EST

Provide five keyctl functions that permit userspace to make use of the new
key type ops for accessing and driving asymmetric keys.

(*) Query an asymmetric key.

long keyctl(KEYCTL_PKEY_QUERY,
key_serial_t key, unsigned long reserved,
struct keyctl_pkey_query *info);

Get information about an asymmetric key. The information is returned
in the keyctl_pkey_query struct:

__u32 supported_ops;

A bit mask of flags indicating which ops are supported. This is
constructed from a bitwise-OR of:

KEYCTL_SUPPORTS_{ENCRYPT,DECRYPT,SIGN,VERIFY}

__u32 key_size;

The size in bits of the key.

__u16 max_data_size;
__u16 max_sig_size;
__u16 max_enc_size;
__u16 max_dec_size;

The maximum sizes in bytes of a blob of data to be signed, a signature
blob, a blob to be encrypted and a blob to be decrypted.

reserved must be set to 0. This is intended for future use to hand
over one or more passphrases needed unlock a key.

If successful, 0 is returned. If the key is not an asymmetric key,
EOPNOTSUPP is returned.


(*) Encrypt, decrypt, sign or verify a blob using an asymmetric key.

long keyctl(KEYCTL_PKEY_ENCRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_DECRYPT,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_SIGN,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
void *out);

long keyctl(KEYCTL_PKEY_VERIFY,
const struct keyctl_pkey_params *params,
const char *info,
const void *in,
const void *in2);

Use an asymmetric key to perform a public-key cryptographic operation
a blob of data.

The parameter block pointed to by params contains a number of integer
values:

__s32 key_id;
__u32 in_len;
__u32 out_len;
__u32 in2_len;

For a given operation, the in and out buffers are used as follows:

Operation ID in,in_len out,out_len in2,in2_len
======================= =============== =============== ===========
KEYCTL_PKEY_ENCRYPT Raw data Encrypted data -
KEYCTL_PKEY_DECRYPT Encrypted data Raw data -
KEYCTL_PKEY_SIGN Raw data Signature -
KEYCTL_PKEY_VERIFY Raw data - Signature

info is a string of key=value pairs that supply supplementary
information.

The __spare space in the parameter block must be set to 0. This is
intended, amongst other things, to allow the passing of passphrases
required to unlock a key.

If successful, encrypt, decrypt and sign all return the amount of data
written into the output buffer. Verification returns 0 on success.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

Documentation/security/keys/core.rst | 111 ++++++++++++
include/uapi/linux/keyctl.h | 25 +++
security/keys/Makefile | 1
security/keys/compat.c | 18 ++
security/keys/internal.h | 39 ++++
security/keys/keyctl.c | 24 +++
security/keys/keyctl_pkey.c | 323 ++++++++++++++++++++++++++++++++++
7 files changed, 541 insertions(+)
create mode 100644 security/keys/keyctl_pkey.c

diff --git a/Documentation/security/keys/core.rst b/Documentation/security/keys/core.rst
index 2cdccde6c585..3d36f42283e6 100644
--- a/Documentation/security/keys/core.rst
+++ b/Documentation/security/keys/core.rst
@@ -859,6 +859,7 @@ The keyctl syscall functions are:
and either the buffer length or the OtherInfo length exceeds the
allowed length.

+
* Restrict keyring linkage::

long keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring,
@@ -890,6 +891,116 @@ The keyctl syscall functions are:
applicable to the asymmetric key type.


+ * Query an asymmetric key::
+
+ long keyctl(KEYCTL_PKEY_QUERY,
+ key_serial_t key_id, unsigned long reserved,
+ struct keyctl_pkey_query *info);
+
+ Get information about an asymmetric key. The information is returned in
+ the keyctl_pkey_query struct::
+
+ __u32 supported_ops;
+ __u32 key_size;
+ __u16 max_data_size;
+ __u16 max_sig_size;
+ __u16 max_enc_size;
+ __u16 max_dec_size;
+ __u32 __spare[10];
+
+ ``supported_ops`` contains a bit mask of flags indicating which ops are
+ supported. This is constructed from a bitwise-OR of::
+
+ KEYCTL_SUPPORTS_{ENCRYPT,DECRYPT,SIGN,VERIFY}
+
+ ``key_size`` indicated the size of the key in bits.
+
+ ``max_*_size`` indicate the maximum sizes in bytes of a blob of data to be
+ signed, a signature blob, a blob to be encrypted and a blob to be
+ decrypted.
+
+ ``__spare[]`` must be set to 0. This is intended for future use to hand
+ over one or more passphrases needed unlock a key.
+
+ If successful, 0 is returned. If the key is not an asymmetric key,
+ EOPNOTSUPP is returned.
+
+
+ * Encrypt, decrypt, sign or verify a blob using an asymmetric key::
+
+ long keyctl(KEYCTL_PKEY_ENCRYPT,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_DECRYPT,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_SIGN,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ void *out);
+
+ long keyctl(KEYCTL_PKEY_VERIFY,
+ const struct keyctl_pkey_params *params,
+ const char *info,
+ const void *in,
+ const void *in2);
+
+ Use an asymmetric key to perform a public-key cryptographic operation a
+ blob of data. For encryption and verification, the asymmetric key may
+ only need the public parts to be available, but for decryption and signing
+ the private parts are required also.
+
+ The parameter block pointed to by params contains a number of integer
+ values::
+
+ __s32 key_id;
+ __u32 in_len;
+ __u32 out_len;
+ __u32 in2_len;
+
+ ``key_id`` is the ID of the asymmetric key to be used. ``in_len`` and
+ ``in2_len`` indicate the amount of data in the in and in2 buffers and
+ ``out_len`` indicates the size of the out buffer as appropriate for the
+ above operations.
+
+ For a given operation, the in and out buffers are used as follows::
+
+ Operation ID in,in_len out,out_len in2,in2_len
+ ======================= =============== =============== ===============
+ KEYCTL_PKEY_ENCRYPT Raw data Encrypted data -
+ KEYCTL_PKEY_DECRYPT Encrypted data Raw data -
+ KEYCTL_PKEY_SIGN Raw data Signature -
+ KEYCTL_PKEY_VERIFY Raw data - Signature
+
+ ``info`` is a string of key=value pairs that supply supplementary
+ information. These include:
+
+ ``enc=<encoding>`` The encoding of the encrypted/signature blob. This
+ can be "pkcs1" for RSASSA-PKCS1-v1.5 or
+ RSAES-PKCS1-v1.5; "pss" for "RSASSA-PSS"; "oaep" for
+ "RSAES-OAEP". If omitted or is "raw", the raw output
+ of the encryption function is specified.
+
+ ``hash=<algo>`` If the data buffer contains the output of a hash
+ function and the encoding includes some indication of
+ which hash function was used, the hash function can be
+ specified with this, eg. "hash=sha256".
+
+ The ``__spare[]`` space in the parameter block must be set to 0. This is
+ intended, amongst other things, to allow the passing of passphrases
+ required to unlock a key.
+
+ If successful, encrypt, decrypt and sign all return the amount of data
+ written into the output buffer. Verification returns 0 on success.
+
+
Kernel Services
===============

diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index d5eac15bc00c..1a5a7948606e 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -61,6 +61,11 @@
#define KEYCTL_INVALIDATE 21 /* invalidate a key */
#define KEYCTL_GET_PERSISTENT 22 /* get a user's persistent keyring */
#define KEYCTL_DH_COMPUTE 23 /* Compute Diffie-Hellman values */
+#define KEYCTL_PKEY_QUERY 24 /* Query public key parameters */
+#define KEYCTL_PKEY_ENCRYPT 25 /* Encrypt a blob using a public key */
+#define KEYCTL_PKEY_DECRYPT 26 /* Decrypt a blob using a public key */
+#define KEYCTL_PKEY_SIGN 27 /* Create a public key signature */
+#define KEYCTL_PKEY_VERIFY 28 /* Verify a public key signature */
#define KEYCTL_RESTRICT_KEYRING 29 /* Restrict keys allowed to link to a keyring */

/* keyctl structures */
@@ -82,4 +87,24 @@ struct keyctl_kdf_params {
#define KEYCTL_SUPPORTS_SIGN 0x04
#define KEYCTL_SUPPORTS_VERIFY 0x08

+struct keyctl_pkey_query {
+ __u32 supported_ops; /* Which ops are supported */
+ __u32 key_size; /* Size of the key in bits */
+ __u16 max_data_size; /* Maximum size of raw data to sign in bytes */
+ __u16 max_sig_size; /* Maximum size of signature in bytes */
+ __u16 max_enc_size; /* Maximum size of encrypted blob in bytes */
+ __u16 max_dec_size; /* Maximum size of decrypted blob in bytes */
+ __u32 __spare[10];
+};
+
+struct keyctl_pkey_params {
+ __s32 key_id; /* Serial no. of public key to use */
+ __u32 in_len; /* Input data size */
+ union {
+ __u32 out_len; /* Output buffer size (encrypt/decrypt/sign) */
+ __u32 in2_len; /* 2nd input data size (verify) */
+ };
+ __u32 __spare[7];
+};
+
#endif /* _LINUX_KEYCTL_H */
diff --git a/security/keys/Makefile b/security/keys/Makefile
index ef1581b337a3..9cef54064f60 100644
--- a/security/keys/Makefile
+++ b/security/keys/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_SYSCTL) += sysctl.o
obj-$(CONFIG_PERSISTENT_KEYRINGS) += persistent.o
obj-$(CONFIG_KEY_DH_OPERATIONS) += dh.o
+obj-$(CONFIG_ASYMMETRIC_KEY_TYPE) += keyctl_pkey.o

#
# Key types
diff --git a/security/keys/compat.c b/security/keys/compat.c
index e87c89c0177c..9482df601dc3 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -141,6 +141,24 @@ COMPAT_SYSCALL_DEFINE5(keyctl, u32, option,
return keyctl_restrict_keyring(arg2, compat_ptr(arg3),
compat_ptr(arg4));

+ case KEYCTL_PKEY_QUERY:
+ if (arg3 != 0)
+ return -EINVAL;
+ return keyctl_pkey_query(arg2,
+ compat_ptr(arg4),
+ compat_ptr(arg5));
+
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ case KEYCTL_PKEY_SIGN:
+ return keyctl_pkey_e_d_s(option,
+ compat_ptr(arg2), compat_ptr(arg3),
+ compat_ptr(arg4), compat_ptr(arg5));
+
+ case KEYCTL_PKEY_VERIFY:
+ return keyctl_pkey_verify(compat_ptr(arg2), compat_ptr(arg3),
+ compat_ptr(arg4), compat_ptr(arg5));
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 9f8208dc0e55..74cb0ff42fed 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -298,6 +298,45 @@ static inline long compat_keyctl_dh_compute(
#endif
#endif

+#ifdef CONFIG_ASYMMETRIC_KEY_TYPE
+extern long keyctl_pkey_query(key_serial_t,
+ const char __user *,
+ struct keyctl_pkey_query __user *);
+
+extern long keyctl_pkey_verify(const struct keyctl_pkey_params __user *,
+ const char __user *,
+ const void __user *, const void __user *);
+
+extern long keyctl_pkey_e_d_s(int,
+ const struct keyctl_pkey_params __user *,
+ const char __user *,
+ const void __user *, void __user *);
+#else
+static inline long keyctl_pkey_query(key_serial_t id,
+ const char __user *_info,
+ struct keyctl_pkey_query __user *_res)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long keyctl_pkey_verify(const struct keyctl_pkey_params __user *params,
+ const char __user *_info,
+ const void __user *_in,
+ const void __user *_in2)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline long keyctl_pkey_e_d_s(int op,
+ const struct keyctl_pkey_params __user *params,
+ const char __user *_info,
+ const void __user *_in,
+ void __user *_out)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
/*
* Debugging key validation
*/
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 1ffe60bb2845..18619690ce77 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1747,6 +1747,30 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
(const char __user *) arg3,
(const char __user *) arg4);

+ case KEYCTL_PKEY_QUERY:
+ if (arg3 != 0)
+ return -EINVAL;
+ return keyctl_pkey_query((key_serial_t)arg2,
+ (const char __user *)arg4,
+ (struct keyctl_pkey_query *)arg5);
+
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ case KEYCTL_PKEY_SIGN:
+ return keyctl_pkey_e_d_s(
+ option,
+ (const struct keyctl_pkey_params __user *)arg2,
+ (const char __user *)arg3,
+ (const void __user *)arg4,
+ (void __user *)arg5);
+
+ case KEYCTL_PKEY_VERIFY:
+ return keyctl_pkey_verify(
+ (const struct keyctl_pkey_params __user *)arg2,
+ (const char __user *)arg3,
+ (const void __user *)arg4,
+ (const void __user *)arg5);
+
default:
return -EOPNOTSUPP;
}
diff --git a/security/keys/keyctl_pkey.c b/security/keys/keyctl_pkey.c
new file mode 100644
index 000000000000..783978842f13
--- /dev/null
+++ b/security/keys/keyctl_pkey.c
@@ -0,0 +1,323 @@
+/* Public-key operation keyctls
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@xxxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/key.h>
+#include <linux/keyctl.h>
+#include <linux/parser.h>
+#include <linux/uaccess.h>
+#include <keys/user-type.h>
+#include "internal.h"
+
+static void keyctl_pkey_params_free(struct kernel_pkey_params *params)
+{
+ kfree(params->info);
+ key_put(params->key);
+}
+
+enum {
+ Opt_err = -1,
+ Opt_enc, /* "enc=<encoding>" eg. "enc=oaep" */
+ Opt_hash, /* "hash=<digest-name>" eg. "hash=sha1" */
+};
+
+static const match_table_t param_keys = {
+ { Opt_enc, "enc=%s" },
+ { Opt_hash, "hash=%s" },
+ { Opt_err, NULL }
+};
+
+/*
+ * Parse the information string which consists of key=val pairs.
+ */
+static int keyctl_pkey_params_parse(struct kernel_pkey_params *params)
+{
+ unsigned long token_mask = 0;
+ substring_t args[MAX_OPT_ARGS];
+ char *c = params->info, *p, *q;
+ int token;
+
+ while ((p = strsep(&c, " \t"))) {
+ if (*p == '\0' || *p == ' ' || *p == '\t')
+ continue;
+ token = match_token(p, param_keys, args);
+ if (__test_and_set_bit(token, &token_mask))
+ return -EINVAL;
+ q = args[0].from;
+ if (!q[0])
+ return -EINVAL;
+
+ switch (token) {
+ case Opt_enc:
+ params->encoding = q;
+ break;
+
+ case Opt_hash:
+ params->hash_algo = q;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Interpret parameters. Callers must always call the free function
+ * on params, even if an error is returned.
+ */
+static int keyctl_pkey_params_get(key_serial_t id,
+ const char __user *_info,
+ struct kernel_pkey_params *params)
+{
+ key_ref_t key_ref;
+ void *p;
+ int ret;
+
+ memset(params, 0, sizeof(*params));
+ params->encoding = "raw";
+
+ p = strndup_user(_info, PAGE_SIZE);
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+ params->info = p;
+
+ ret = keyctl_pkey_params_parse(params);
+ if (ret < 0)
+ return ret;
+
+ key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
+ if (IS_ERR(key_ref))
+ return PTR_ERR(key_ref);
+ params->key = key_ref_to_ptr(key_ref);
+
+ if (!params->key->type->asym_query)
+ return -EOPNOTSUPP;
+
+ return 0;
+}
+
+/*
+ * Get parameters from userspace. Callers must always call the free function
+ * on params, even if an error is returned.
+ */
+static int keyctl_pkey_params_get_2(const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ int op,
+ struct kernel_pkey_params *params)
+{
+ struct keyctl_pkey_params uparams;
+ struct kernel_pkey_query info;
+ int ret;
+
+ memset(params, 0, sizeof(*params));
+ params->encoding = "raw";
+
+ if (copy_from_user(&uparams, _params, sizeof(uparams)) != 0)
+ return -EFAULT;
+
+ ret = keyctl_pkey_params_get(uparams.key_id, _info, params);
+ if (ret < 0)
+ return ret;
+
+ ret = params->key->type->asym_query(params, &info);
+ if (ret < 0)
+ return ret;
+
+ switch (op) {
+ case KEYCTL_PKEY_ENCRYPT:
+ case KEYCTL_PKEY_DECRYPT:
+ if (uparams.in_len > info.max_enc_size ||
+ uparams.out_len > info.max_dec_size)
+ return -EINVAL;
+ break;
+ case KEYCTL_PKEY_SIGN:
+ case KEYCTL_PKEY_VERIFY:
+ if (uparams.in_len > info.max_sig_size ||
+ uparams.out_len > info.max_data_size)
+ return -EINVAL;
+ break;
+ default:
+ BUG();
+ }
+
+ params->in_len = uparams.in_len;
+ params->out_len = uparams.out_len;
+ return 0;
+}
+
+/*
+ * Query information about an asymmetric key.
+ */
+long keyctl_pkey_query(key_serial_t id,
+ const char __user *_info,
+ struct keyctl_pkey_query __user *_res)
+{
+ struct kernel_pkey_params params;
+ struct kernel_pkey_query res;
+ long ret;
+
+ memset(&params, 0, sizeof(params));
+
+ ret = keyctl_pkey_params_get(id, _info, &params);
+ if (ret < 0)
+ goto error;
+
+ ret = params.key->type->asym_query(&params, &res);
+ if (ret < 0)
+ goto error;
+
+ ret = -EFAULT;
+ if (copy_to_user(_res, &res, sizeof(res)) == 0 &&
+ clear_user(_res->__spare, sizeof(_res->__spare)) == 0)
+ ret = 0;
+
+error:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}
+
+/*
+ * Encrypt/decrypt/sign
+ *
+ * Encrypt data, decrypt data or sign data using a public key.
+ *
+ * _info is a string of supplementary information in key=val format. For
+ * instance, it might contain:
+ *
+ * "enc=pkcs1 hash=sha256"
+ *
+ * where enc= specifies the encoding and hash= selects the OID to go in that
+ * particular encoding if required. If enc= isn't supplied, it's assumed that
+ * the caller is supplying raw values.
+ *
+ * If successful, the amount of data written into the output buffer is
+ * returned.
+ */
+long keyctl_pkey_e_d_s(int op,
+ const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ const void __user *_in,
+ void __user *_out)
+{
+ struct kernel_pkey_params params;
+ void *in, *out;
+ long ret;
+
+ ret = keyctl_pkey_params_get_2(_params, _info, op, &params);
+ if (ret < 0)
+ goto error_params;
+
+ ret = -EOPNOTSUPP;
+ if (!params.key->type->asym_eds_op)
+ goto error_params;
+
+ switch (op) {
+ case KEYCTL_PKEY_ENCRYPT:
+ params.op = kernel_pkey_encrypt;
+ break;
+ case KEYCTL_PKEY_DECRYPT:
+ params.op = kernel_pkey_decrypt;
+ break;
+ case KEYCTL_PKEY_SIGN:
+ params.op = kernel_pkey_sign;
+ break;
+ default:
+ BUG();
+ }
+
+ in = memdup_user(_in, params.in_len);
+ if (IS_ERR(in)) {
+ ret = PTR_ERR(in);
+ goto error_params;
+ }
+
+ ret = -ENOMEM;
+ out = kmalloc(params.out_len, GFP_KERNEL);
+ if (!out)
+ goto error_in;
+
+ ret = params.key->type->asym_eds_op(&params, in, out);
+ if (ret < 0)
+ goto error_out;
+
+ if (copy_to_user(_out, out, ret) != 0)
+ ret = -EFAULT;
+
+error_out:
+ kfree(out);
+error_in:
+ kfree(in);
+error_params:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}
+
+/*
+ * Verify a signature.
+ *
+ * Verify a public key signature using the given key, or if not given, search
+ * for a matching key.
+ *
+ * _info is a string of supplementary information in key=val format. For
+ * instance, it might contain:
+ *
+ * "enc=pkcs1 hash=sha256"
+ *
+ * where enc= specifies the signature blob encoding and hash= selects the OID
+ * to go in that particular encoding. If enc= isn't supplied, it's assumed
+ * that the caller is supplying raw values.
+ *
+ * If successful, 0 is returned.
+ */
+long keyctl_pkey_verify(const struct keyctl_pkey_params __user *_params,
+ const char __user *_info,
+ const void __user *_in,
+ const void __user *_in2)
+{
+ struct kernel_pkey_params params;
+ void *in, *in2;
+ long ret;
+
+ ret = keyctl_pkey_params_get_2(_params, _info, KEYCTL_PKEY_VERIFY,
+ &params);
+ if (ret < 0)
+ goto error_params;
+
+ ret = -EOPNOTSUPP;
+ if (!params.key->type->asym_verify_signature)
+ goto error_params;
+
+ in = memdup_user(_in, params.in_len);
+ if (IS_ERR(in)) {
+ ret = PTR_ERR(in);
+ goto error_params;
+ }
+
+ in2 = memdup_user(_in2, params.in2_len);
+ if (IS_ERR(in2)) {
+ ret = PTR_ERR(in2);
+ goto error_in;
+ }
+
+ params.op = kernel_pkey_verify;
+ ret = params.key->type->asym_verify_signature(&params, in, in2);
+
+ kfree(in2);
+error_in:
+ kfree(in);
+error_params:
+ keyctl_pkey_params_free(&params);
+ return ret;
+}